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Big pregnancy = Big baby at birth

Here's another reason to keep a bit of an eye on your weight gain in pregnancy - the more kilos a pregnant woman piles on, the higher the chance of giving birth to a bigger than usual baby.

A study of more than 500,000 pregnant women, which was published in the medical journal The Lancet recently, has found that that for every kilogram a woman puts on during pregnancy, her baby gains 7.35 grams.

Women who gained more than 24 kilograms in their pregnancy were more than twice as likely to have a baby whose weight was in the 95th percentile on the charts - that is, over 4kg - than women who gained 8-10kg.

While having a large bouncing baby has long been applauded, this research concluded that high birth weight babies had a higher risk of becoming obese adults with associated diseases such as asthma and cancer.

Large babies born to overweight women also carried a higher risk of jaundice and low blood-sugar levels after birth because of the mothers' higher-than-usual intake of sugar during pregnancy.

The ideal weight gain during pregnancy

Obviously, weight gain in pregnancy varies from woman to woman but the Royal Women's Hospital in Melbourne says a healthy weight gain is 10 and 13kg.

Here is a breakdown of where this weight might go in the average pregnancy:

3.3 kg -the baby

700g - the placenta

800g - amniotic fluid

400g - your breasts

4kg - fat stores to support you during pregnancy and, after birth, breastfeeding

1.2kg - extra fluid

1.2kg - increased blood volume

Don't obsess about your pregnancy weight

In Australia now, it's no longer routine to get weighed at every visit during your pregnancy. So it seems that a mum's weight is not a major issue to health professionals.

But according to a recent US study, it remains a focus for pregnant women with almost 10% of mums-to-be trying to lose weight while pregnant, and more than a third trying to maintain their pre-pregnancy weight throughout their pregnancy.

The Royal Women's Hospital stresses the importance of not trying to lose weight during your pregnancy, acknowledging the negative impact “celebrity pregnancies” have had on women.

“But every woman is different, our body shapes are very different and pregnancy affects us in different ways,” the hospital says. “The most common-sense approach is to stay healthy; fill up on healthy foods, don't deny yourself occasional treats, exercise within your own limits and celebrate your body's ability to produce life.”